DYNAGEN is a Cisco router/switch emulator which uses original Cisco IOS.This makes it work just like a router in real world. With the help of this software, you can practice your CCNA/CCNP/CCIE network lab topologies on your PC while having the experience of real world topologies. The following video shows you how to download and install DYNAGEN on your PC.

DYNAGEN is a best Cisco emulator ever written. You can take advantage of that as it is free to use. Download it as follows:

http://sourceforge.net/project/showfiles.php?group_id=160317&package_id=192619